Etching solution, method of etching and printed wiring board

Abstract

There is provided an etching solution comprised of a cupric chloride solution and a high-concentration triazole type compound added to the cupric chloride solution and capable of forming an etching-inhibiting coating. In a process of forming a circuit pattern by etching with the etching solution, an etching-inhibiting coating is selected formed on parts of a copper foil laid under the edge of an etching resist to effectively inhibit horizontal side-etching of the copper foil from the edge of the etching resist. Also, nonuniform irregularities formed on the side wall of the circuit pattern by the etching improves the adhesion between the circuit pattern and an insulating resin layer covering the circuit pattern.

Description

FIELD OF THE INVENTION [0001] The present invention generally relates to an etching solution intended for use in the process of etching a copper layer to form an electrical circuit, and more particularly to an etching solution having mixed therein an additive containing a component that will form a coating effectively inhibiting the etching, and which is thus capable of anisotropic etching (high etch factor) even in processing a metallic material such as copper, an etching method in which the etching solution is used, and to a printed wiring board having a wiring pattern formed by the etching method. BACKGROUND ART [0002] With the recent remarkable innovation of the electronics, the industries of printed wiring boards are strictly urged to provide inexpensive high-density wiring boards. However, etching in the conventional subtractive method (tinting method) permits isotropic forming of a circuit pattern. With this etching technique, it is difficult to make etching in any intended d...

AI Technical Summary

Benefits of technology

[0019] As proved by the results of the experiments having been done by the inventors of the present invention, the effect of side-etching inhibition in the etching using the etching solution according to the present invention is two to three times higher than that (on the order of 30%) in the etching using the etching solution disclosed in the Japanese Patent Application Laid Open No. 2003-306784. That is, the effect of side-etching inhibition of the etching solution according to the present invention is 80 to 90%.

[0020] According to the present invention, the triazole type compound can be solved in a high concentration in the above-mentioned etching solution using the surface active agent or using a strong alkali or acid in stead of the surface active agent. Both these methods are nearly equal in effect to each other.

Problems solved by technology

With this etching technique, it is difficult to make etching in any intended direction, and provide inexpensive high-density wiring boards.

Since a wiring interval should be determined taking the side etching in consideration in designing a high-density wiring, it is difficult to attain a high density of wiring.

However, the conventional additive method includes complicated processes and thus cannot have yielded any inexpensive printed wiring boards as final products.

However, although the Japanese Patent Application Laid Open Nos. 2003-306784 and 2003-306784 discloses the additive that will inhibit the side etching made by the cupric chloride and ferric chloride in the etching process, a most effective one selected from among such additives attains such an inhibition about 30% higher than with the conventional etching solutions and this effect of side-etching inhibition is not sufficient for forming a high-density wiring.

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